Each layer protocol entity in each layer structure of the existing Internet except the physical layer has its own name space, comprising a MAC address of a link layer, an IP address of a network layer, an IP address and a port number of a transmission layer and a domain name of an application layer. In theses name spaces, the MAC address is unique in a subnet only and the port number is unique in a host only; thus, two important global name spaces, i.e., the IP address and the domain name exist in the Internet. The domain name and the IP address realize analysis through DNS. In such kind of name spaces structure, the IP address has a dual-function of acting as the location identifier of communication terminal host network interface of network layer in network topology and also acting as the identity of transmission layer host network interface.
The TCP/IP protocol does not consider the mobility of host at the beginning of the design; along with the development of Next Generation Networks (NGN), the user mobility and host multihoming problems become more and more common and the semantic overload defects of such kind of IP address are increasingly clear. When the IP address of a host changes, both the route and the identity of communication terminal host change; the change of route is acceptable, but the change of host identifier will cause the interruption of application and connection.
The industry presents an ID/Locator Separation (IPSPLIT, ID/locator separation in NGN) technology for supporting the mobility and multihoming and supporting the calling continuity. The IPSPLIT technology takes a host identifier (Host ID) as the identity of host, which uniquely marks each host connected to Internet globally. It aims at separating the transmission layer from the network layer, providing a secure host mobility and multihomed method for the Internet, and providing an encrypted host identifier name space for easy authentication of communication parts and implementing a secure, reliable network system. In an IPSPLIT network, the IP address only represents the routing location of communication terminal host in network topology. The technology solves the semantic overload problem of IP address, separates the dual-function of IP address and realizes the support to problems of multi-mobility, multihoming, IP address dynamic reassignment and access between different network regions.
The IPSPLIT technology is based on the NGN. In the IPSPLIT network, a user may be mobile or multihomed; and then a IP address of the user is not uniquely assigned; a host identifier is corresponding to a plurality of IP addresses. Therefore, the multihoming and mobility problems are solved. The host identifier of a multihoming device corresponds to a plurality of IP addresses; if an IP address is unusable, or a better IP address exists, the built transmission layer connection may be transferred to other IP addresses easily. The IP address may change due to the mobility of host, however, the host identifier does not change, consequently, the connection of transmission layers do not have to be interrupted, but the moved node should know the change of IP address. The transmission layer connection is bound with the host identifier and the IP address is only used in routing. Thus, the IPSPLIT technology implements the exchange access of different network regions, such as the public network and the private network, the IPv4 network and the IPv6 network.
The NGN system structure is as shown in FIG. 1, comprising a network access control part, a resource control part, a transport part, a service control part and a user terminal/user network part.
The network access control part provides functions of a registration, an authentication and authorization, an address assignment, a parameter allocation and a location management, etc., for a user terminal/user network of the NGN network, such as the network attachment control functions in an ITU-T NGN network;
the resource control part fulfills functions of a admission control, a resource reservation, etc. when a user terminal/user network accesses to the network based on a strategy and network resource state, such as resource and admission control functions in TU-T NGN network, access management functions in the NGN;
the transport part fulfills the information transport function, such as transport functions in the ITU-T NGN network;
a service control part belongs to a part of the service layer and fulfills in service layer the functions of a registration, an authentication and authorization, a resource control, etc., such as the service terminal authentication and authorization processes in the ITU-T NGN network;
a user terminal/user network part provides a network access function for a user, such as a user equipment in the ITU-T NGN network;
The NGN system structure based on the IPSPLIT is as shown in FIG. 2, wherein the functions of the network access control part, the resource control part, the transport part, the service control part and the user terminal/user network part are consistent with that in the conventional NGN system. The ID/locator separation control part is a special functional part of the NGN system structure based on the IPSPLIT.
The NGN system functional frame based on the IPSPLIT is as shown in FIG. 3, the function of each functional entity are as the follows:
a Transport User Profile Functional Entity (TUP-FE) is used for storing user information related to the transport layer;
a Transport Authentication And Authorization Functional Entity (TAA-FE) is configured to provide a transport layer authentication and authorization function and check the network access authentication and authorization of a user based on the user information;
an Access Management Functional Entity (AM-FE) is configured to apply a translation conversion to a network access request initiated by a user and send the request of assigning IP address and other network allocation parameters to a NAC-FE;
a Transport Location Management Functional Entity (TLM-FE) is configured to register an IP address assigned to a user and other network location information provided by the NAC-FE;
a network access configuration functional entity (NAC-FE) is configured to assign an IP address for a user terminal, and possibly assign other network allocation parameters for a user terminal, such as an address of a DNS server and an address of a signaling agency etc.
an ID/Locator mapping functional entity (ILM-FE, Id-loc-Mapping Functional Entity) is configured to store a mapping and a dynamic update of an ID/LOC.
The transmission location management in the NGN is implemented through the interaction of the service control layer (SCF) and the TLM-FE. The SCF obtains a characteristic of an IP connection session needed in a service control, such as network location information of a user, an IP address of a user, a characteristic of a UE and a SCF characteristic. The implementation process of the transmission location management in NGN is as shown in Steps 301-302 in FIG. 4. The SCF inquires a transmission location from the TLM-FE and the TLM-FE sends the transmission location response to the SCF.
The transmission layer service control process is implemented through the interaction between the SCF and the TLM-FE in the process. In the NGN network based on the ID/locator separation, if the transmission layer service control process manages the transmission location through the SCF and the TLM-FE, defects thereof are as the follows:
firstly, only one IP address exists at the same moment as for the TLM-FE; in the NGN network based on the ID/locator separation, multiple usable IP addresses exist at the same moment as for a multihoming user, which means that the service control layer can select one from the multiple usable IP addresses;
secondly, in the NGN network based on the ID/locator separation, the transmission service control layer manages a location through a user identifier of a user; thus, the user identifier will not change even when the user location changes, ensuring the service contiguity. In the NGN network based on the ID/locator separation, the TLM-FE is not in charge of storing the user identifier; if the location management is executed through the user identifier, the service transmission layer service control process is impossible to manages transmission location through the SCF and the TLM-FE.